when latter is laid back; caudal fin without secondary- 

 keels, with only the primajry keels formed by the lateral 

 expansion of the caudal peduncle. 



Isurus Rafinesque, I8IO 



Bigelow and Schroeder (19^8) placed these genera (isuridae) in 

 the suborder Galeoidea, along with eleven other families, accoxinting 

 for the bulk of modern shark species. 



Considerable variation exists in the treatment of this family 

 by past workers. Regan (1906) placed the Lamnidae in his division 

 Galeoidei, under the suborder Pleurotremata. Garman (1913) adopted 

 the following classification: 



Suborder: Antacea 



Group: Isuroidei (= super family) 

 Families: Vulpeculidae 

 Isuridae 

 Rhincodontidae 



He included the basking shark ( Cetorhinus ) with the Isuridae, did 

 not distinguish between Lamna and Isurus in his generic key, and 

 referred the species of Tamna to Isurus (the older name). 



White's (1937) revision of the Galeold sharks was based pri- 

 marily on vertebral structure and other internal characters. She 

 arrived at the following arrangement: 



Subclass: Plagiostoma 

 Superorder: Antacea 

 Order: Galea 



Suborder: Isurida 



Superfamily: Isuroidea 

 Families: Vulpeculidae 

 Isuridae 

 Cetorhinidae 



In addition to establishing a separate family (Cetorhinidae) for 

 the basking shark, she removed the Rhineodontidae (Rhincodontidae, 

 the whale sharks) from Gajrman's grouping and placed them with the 

 Orectoloboidea (the niorse and carpet sharks). She followed Garman 

 in not distinguishing between Tamna and Isurus . 



Berg (19^0) proposed the following scheme: 



Subclass: Selachii 



Order: Tamni formes (Galeoidei) 

 Suborder: Lamnoidei (isurida) 

 Family: Lamnidae (isuridae) 

 Subfamilies: Alopiini 

 Lamnini 

 Cetorhinini 



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